With the development of liquid crystal display technology, an important direction is to enhance colour gamut of liquid crystal display device. Current, the colour gamut of the liquid crystal display device is enhancing to 95% NTSC from the beginning of 70% NTSC, and then enhances to 120% NTSC. When the colour gamut of the liquid crystal display device from 70% NTSC enhancing to 95% NTSC, most of problem from the backlight to color photoresist already be overcome. However, when the colour gamut of the liquid crystal display device is enhancing to 120% NTSC, a lot of audiences give response for reduce the eye-comfort of solid color image. The probably reason is because the pure color of high color gamut is beyond the nature color range, and human's eyes never see this color before and feel strange. Therefore, it decreases the high color gamut acceptance on marketing. Until now, there still does not have any better solution.